Method of making inorganic oxides



Patented Sept; 3, 1929.

No Drawing. Original applic This invention relates of ferro-ferriccompounds, especially fro from mineral acid ferric METHOD OF MAKINGINORGANIC ation filed October 26, 1822, Serial No. 597,181 filed October26, 1922. Serial No. 597,182.

to the production oxide pigments from ferric 1n ferric voxide and salts.and has for its particular objects the economical and expeditiousproduction of such a product in a condition suitable for use in printinginks, paints or like purposes for which such pigments are peculiarlysuited.

Heretofore it has been to utlhze ferrous salts in In as a final producta was sought. Such salts.

the usual practice operations where ferro ferric oxide however. are notalways available at a price which renders the use thereof preferable toferr c salts.

especially if ferric oxide in the form of pyrites cinder andhydrochloric acid a re both available at relatively cheap prices.

y investigations have led to the discovery that ferric compounds, eitherin the form of ferric oxide such as iron ore. or iron cinders, or elsein the form of soluble ferric salts, such for example as ferric sul hateor ferric chloride, are especially suitable for the manufactureofferroferric oxide pigments of hlgh tlnctorial strength, of variousshades and of extremely and composition.

uniform character In carrying out my invention, I preferably proceed asfollows Twelve (12) parts of ferric oxide (F0203),

for example iron cinder ob tained from pyrites burners are dissolvedinfifty (50) parts of 20 B. hydrochloric acid When the ferric oxide iscompletely dissolved in the foree'olng concentrated acid the with threehundred (300) mixture is diluted parts of water. A

mixture of twenty-seven (27) parts of soda ash in one hundred (100)partsof water is then slowly added to the foregoing ferric chloridesolution while the latter is still. cold, in order to effect thepreciptation of ferric hydroxide.

Following the addition of the sodium carbonate solution. the temperatureof the mixture 'ispreferably raised to about 180 F. and the heating itis evident that the precipitation is com plete.

In order to obtain my is continued until improved pigment in the desiredshade and strength, it now becomes necessary to cite cutting back of thefer ct the reversion or ric oxide to an in OXIDES. V

Divided and this application going mixture of a solution of nine. (9)parts of copperas in forty-two (42) parts of water. The iron sulphatewhichis added for the purpose of cutting back the mixture effects theprecipitation of ferrous oxide and sodium sulphate as a result of thereaction between the excess sodium carbonate confained in the mixtureand the ferrous sulphate employed for the cutting back operation.

The foregoing process, it is believed, is represented by the followingequations:

Feb, 6HC1= QFeCl 31-1 0. 3H O EZFeCl iNa CO 2Fe(OH) +6NaCl+3COThe-cutting back operation may be represented by the following equation:QFeCO' 2Na. ,CO 211 0 2Fe(OH) +2Na SO,+2CO,. It is evident that theresultant product will consist of an intimate combination of ferric andferrous oxides and that the shade The final product resulting from theout ing back operation is separated by filtration 1n the usual mannerand then dried at a temperature of from 180 F. to 200 F. Obviously theresultant product may contain some iron as hydroxide, the amountdepending upon the temperature and time of the drying,-butessentially itcomprises a ferroferric oxide.

The ferrous oxide formed from the ferrous salt introduced in which Iterm the cutting back operation becomes homogeneously combined, bothphysically and chemically. with the entire mass of ferric hydroxide andas aconsequence, as hereinafter stated, a product more uniform instrength and color is obtainable than can be accomplished were itattempted to secure such intermediate procluct by the partial orincomplete oxidation of soluble or insoluble ferrous salts.

-Fi. lrthermore, my improved process Among the several advantages of myprocess is the fact that, unlikethose processes wherein the oxidation ofiron hydroxide is carried but partially to completion, the shade of theresultant product can be very accurately predetermined thru the controlof the amount of the ferrous salt employed for the cutting backoperation and consequently it is possible, as heretofore stated, to turnout successive batches of product each of practically the identicalshade and strength. Such accuracy of control is due largely to the factthat in my process the salt operated upon in the final or cutting backoperation is a completely oxidized ferric hydroxide and not a partiallyoxidized iron hydroxide which is susceptible to further oxidation duringthe subsequent heating and drying stages in the process of treatment.

will producepigments of almost any desired shade of yellow, red, brownor black which pigments, because of their extreme fineness, uniformityof color and permanency, are especially suited for use in printing inks,paints and like purposes wherein-a pigment havin such characteristics isadapted.

'If desired, milk of lime can be advantagm ously employed in lieu ofpart or all of the sodium carbonate for the precipitation of the ironoxide as obviously the amount ofcalcium sulphate precipitated will belimited by the quantity of ferrous sulphate present.

Unlike other processes of producing fer-roferric oxides, the operationof my process and the control of the resultant product requires nohighly skilled chemist for the purpose of making periodic quantitativeanalyses of the product as the oxidation progresses, as it is merelynecessary for the operator to test with a test paper saturated withpotassium ferri-cyanide for unoxidized ferrous salts in order toascertain whether all ferrous iron has beenozidized'. Thereafter, sincethe quantity of ferrous salt employed in the cutting back operation ispredetermined, no quantitative analyses is required in the final sta eof the operation, as mere tests with the a oresaid test papers will showwhen all of the ferrous sulphate added has beenconverted into ferroushydroxide.

This application relates to one of the species described in my parentcopending' apmixture suflicientl pliclation No. 597,181 filed of evendate here- Wit WVithout departing from the spirit of my invention,various modifications of the process herein described, within the scopeof the oxide, which consists in dissolving ferric oxide in ahydrochloric acid solution, effecting the precipitation of the iron ionsof the resultant salt as ferric hydroxide in intimate combination withprecipitated ferrous hydroxide by the addition to said mixture of aferrous salt. 7

3. The process of making a ferro-ferric oxide, which consists indissolving ferric oxide in an acid capable of forming a ferric salttherefrom, effecting the precipitation of an insoluble ferric compoundfrom the 'resultant solution by the admixture therewith of a ferroussalt while maintaining the substantially all 0 the ferrous salt as aninsoluble ferrous compound in intimate combination with such insolubleferric compound. 4. The process of making a ferro-ferric oxide, whichconsists in forming a soluble ferric saltfrom an insoluble ferriccompound substantially free from a ferrous compound, and effecting theprecipitation of ferric hydroxide from such ferric salt then intimatelmixing therewith a ferrous salt and efi'ectlng the preci itation in situin said ferric hydroxide o ferrous hydroxide and then separatingsuchferro-ferric hydroxide from such: solution and substantiallyconverting-the same into a ferro-ferric oxide.

. Signed at New York city, in the county and State of New York this 24thday of October, 1922.

- EARL H MeLEOD.

alkaline to precipitate

